The present invention relates to a right-angle connector unit for electrical and removable connection between first and second electric devices, which comprises a first right-angle connector connected to the first electric device, a second right-angle connector connected to the second electric device, and a cable connector having flexibility and removably connecting between the first and the second right-angle connectors.
In a conventional right-angle connector unit of the type described above, the first and the second right-angle connectors comprise a first and a second circuit board, respectively, which will be referred to as a first and a second connector boards, respectively. The first and the second electric devices usually comprise circuit boards, respectively, which will be referred to as a first mother board and a second mother board so as to distinguish them from the first and the second connector boards. The cable connector usually comprises a flexible flat cable or a flexible printed cable.
The first connector board comprises a first base portion or side to be mounted on and face a surface of the first mother board as a connection part of the first electric device, a first vertical portion or side extending substantially in perpendicular to the first base portion, and first through n-th (in which n is an integer but not smaller than 2) conductor strips as primary contacts extending thereon in parallel to one another between the first base portion and the first vertical portion. Herein, the first through the n-th primary contacts have one ends which are arranged in a first direction along the first base portion with spaces left between adjacent ones and are formed into, usually, pin terminals to be connected to the first mother board. The other ends of the first through the n-th primary contacts are also arranged in a direction perpendicular to the first direction along the first vertical portion with spaces left between adjacent ones and are also formed into, usually, pin terminals to be connected to one end of the cable connector. Therefore, it is noted that one of the first and n-th primary contacts relatively near to a corner where the first base and vertical portions intersect is shorter in length than another primary contact relatively remote from the corner, that is, i-th primary contact, i being smaller than n but larger than 1, is longer than an (i-1)-th primary contact.
Likewise, the second connector boards as the second right-angle connector comprises a second base portion to be mounted on the second mother board, a second vertical portion perpendicular to the second base portion, and first through n-th secondary contacts extending thereon in parallel to one another between the second base portion and the second vertical portion. Herein, the first through the n-th secondary contacts have one ends which are arranged in a second direction along the second base portion with spaces left between adjacent ones and are formed into, usually, pin terminals to be connected to the second mother board. The other ends of the first through the n-th secondary contacts are also arranged in a direction perpendicular to the second direction along the second vertical portion with spaces left between adjacent ones and are also formed into, usually, pin terminals to be connected to the other end of the cable connector. Therefore, it is noted that one of the first and n-th secondary contacts relatively near to a corner where the second base and vertical portions intersect is shorter in length than another secondary contact relatively remote from the corner, that is, i-th secondary contact, i being smaller than n but larger than 1, is longer than an (i-1)-th secondary contact.
The cable connector comprises first through n-th conductors equal to one another in length. The first through n-th conductors are provided with socket terminals at opposite ends which are mated with the pin terminals of the first through n-th primary and secondary contacts of the first and second connector boards, respectively. As a result, the first through the n-th conductors are removably connected to the first through the n-th primary contacts of the first right-angle connector and to the first through n-th secondary contacts of the second right-angle connector, respectively.
When the cable connector connects between the first and the second right-angle connectors, the first through the n-th primary contacts of the first right-angle connector and the first through the n-th secondary contacts of the second right-angle connector are connected to one another through the first through the n-th conductors of the cable connector, respectively, to thereby form a plurality of first through n-th signal passes for transmitting signal therethrough, respectively. The first through n-th signal passes are different to one another in length. This is because the i-th primary contact is longer than the (i-1)-th primary contact and the n-th secondary contact is longer than the (i-1)-th secondary contact, while the n-th primary contact and the (i-1)-th primary contact are connected to the i-th secondary contact and the (i-1)-th secondary contact through i-th conductor and (i-1)-th conductor to thereby form i-th signal pass and (i-1)-th signal pass, respectively. Therefore, signals transmitted through the signal passes are different to one another in delay or passage time.
Recently, the right-angle connector unit is requested to transmit high frequency signal at high speed when applied to such electric devices as circuit board provided with a large scale integrated semiconductor chips, a data storage device, and so on. However, the electric devices can not perform their functions at a desired high speed by signal transmission through the conventional right-angle connector unit because the signals transmitted through the signal passes are different to one another in delay time as described above.
In addition, the right-angle connector unit is required to increase a number of signal passes because the electric devices recently tend to have input/output signals increased. In the conventional right-angle connector unit, when the number of signal passes is increased, the numbers of the primary contacts and the secondary contacts are also increased. As a result, there is increased a difference in length between the shortest one (first) and longest one (n-th) of the primary or secondary contacts. Therefore, the largest difference in length among the signal passes is increased. This means that largest time delay is also increased.